As known flavanone compounds, nymphaeol-A, nymphaeol-B, and nymphaeol-C can be enumerated. Regarding these known flavanone compounds, see “K. Yakushijin, K. Shibayama, H. Murata and H. Furukawa: New prenylflavanones from Hernandia nymphaefolia(presl) Kubitzki, Heterocycles, 14, 397-402, 1980”, “W. R. Phillips, N. J. Baj, A. A. L. Gunatilaka and D. G. I. Kingston: C-Geranyl compounds from Mimulus clevelandii, J. Nat. Prod., 59, 495-497, 1996′, and “M. H. Tseng, C. H. Chou, Y. M. Chen and Y. H. Kuo: Allelopathic prenylflavanones from the fallen leaves of Macaranga tanarius, J. Nat. Prod., 64, 827-828, 2001”. Nymphaeol-A is isolated from Hernandia nymphaefolia(presl) Kubitzki, or Mimulus clevelandii. Nymphaeol-B is isolated from Hernandia nymphaefolia(presl) Kubitzki. Nymphaeol-C is isolated from Hernandia nymphaefolia(presl) Kubitzki, or Macaranga tanarius. However, the physiological activities of these flavanone compounds have been hardly elucidated.